The present invention concerns a magnetic head for magnetic recording apparatus and, particularly, it relates to an improvement in Nb materials used therefor and provides a magnetoresistive head suitable for reading for high density magnetic recording.
The Nb material in the present invention is used, particularly, for a shunt film of a magnetic head using a shunt bias type magnetoresistive device having a shunt film for the application of bias. Further, it is also used as an intermediate film between a soft magnetic film and a magnetoresistive film of a magnetic head using a soft bias type magnetoresistive device having a soft magnetic film for the application of bias.
For the shunt film in existent shunt bias type magnetoresistive heads, there have been used, for example, Ti, Ta, Mo, Nb or the like as described in U.S. Pat. No. 4,663,684, Ti, Cr, Ta, Zr, Hf, TiW alloy or the like as described in U.S. Pat. No. 4,914,538 and Cr, Ta, W, Nb or the like as described in U.S. Pat. No. 5,005,096.
For a magnetoresistive film, a Ni-Fe alloy film, Ni-Co alloy film or Ni-Fe-Co film is used usually, and a shunt film is used together with the magnetoresistive film in the state of a dual layer film. Usually, an electric current greater than 10.sup.6 A/cm.sup.2 is supplied and shunted into each of the films, to generate a bias field in the shunt film and cause a resistance change in the magnetoresistive film due to magnetic resistance.
As the properties required for the shunt film, it has to satisfy such conditions that it has an appropriate electric resistance value relative to the magnetoresistive film so as to provide current shunting that causes an optimum bias field in the dual layer film with the magnetoresistive film, causes no reaction as deteriorating the magnetoresistive film in the manufacturing step of a magnetoresistive device, has excellent corrosion resistance and an easy film forming property and shows less scattering of the electric resistance.
Further, as a bias field generation means, there is a soft bias type magnetoresistive head using a soft magnetic film and having a three-layer structure consisting of a soft magnetic film, a spacer metal film and a magnetoresistive film. As the prior art, there can be mentioned U.S. Pat. Nos. 4,663,685 and 5,001,586.
However, in such a three-layer structure, it is useless that a current flows to the soft magnetic film, and high specific resistivity is desired for the spacer metal film in order to prevent the reduction of the current flowing in the magnetoresistive film. Further, It is of course required also for the spacer metal film that the film has reaction resistance, corrosion resistance and easy film forming property, and has no scattering of the electric resistance as described above.